On Tue, Mar 13, 2012 at 1:53 AM, David Miller <davem@xxxxxxxxxxxxx> wrote: > From: Avery Pennarun <apenwarr@xxxxxxxxx> > Date: Tue, 13 Mar 2012 01:36:36 -0400 > >> The last patch in this series implements a new CONFIG_PRINTK_PERSIST option >> that, when enabled, puts the printk buffer in a well-defined memory location >> so that we can keep appending to it after a reboot. The upshot is that, >> even after a kernel panic or non-panic hard lockup, on the next boot >> userspace will be able to grab the kernel messages leading up to it. It >> could then upload the messages to a server (for example) to keep crash >> statistics. > > On some platforms there are formal ways to reserve areas of memory > such that the bootup firmware will know to not touch it on soft resets > no matter what. For example, on Sparc there are OpenFirmware calls to > set aside such an area of soft-reset preserved memory. > > I think some formal agreement with the system firmware is a lot better > when available, and should be explicitly accomodated in these changes > so that those of us with such facilities can very easily hook it up. Sounds good to me. Do you have any pointers? Just use an early_param? If we see the early_param but we can't reserve the requested address, should we fall back to probing or disable the PRINTK_PERSIST mode entirely? Thanks, Avery -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href